Field Experiments on Root-Crops. 501 



etc., sliould be used; for what crops these fertilizers are more 

 specially useful, and how the variable agricultural condition and 

 chemical composition of our fields affects, practically, the 

 efficiency of artifical manures. In short, the rational and 

 profitable application of artificial manures necessitates a much 

 more extended and special practical experience than a person 

 need have who never uses any other than common farmyard- 

 manure. A certain amount of chemical knowledge is thus indis- 

 pensable to the modern farmer who wishes profitably to employ 

 artificial manures on his land. 



Whilst no rational man will consider chemical knowledge in 

 itself a substitute for the experience in the routine of farm work 

 which a person must possess Avho farms for profit, it will be 

 readily conceded that the rudiments of chemistry are very useful, 

 if not indispensable, for the acquisition of a greater amount of 

 practical experience than was required at a time when guano, 

 bones, cScc,, were unknown to the agricultural world. 



Agricultural chemistry, useful as it is to the improving tenant 

 farmer of the present day, is doubly valuable to persons willing 

 to undertake field experiments with special manures. Systematic 

 scientific instruction, such as is given, for instance, at Cirencester 

 College, if it confers not that direct advantage upon the young 

 farmers which some over-sanguine men anticipated, is calculated 

 to improve wonderfully the powers of observation, so as to 

 enable those who have enjoyed the benefit of a liberal education 

 to perform agricultural experiments with that amount of pre- 

 cision and foresight which cannot reasonably be expected from 

 others. 



Many of my farming friends, with much good will, are always 

 ready to begin any experiment which I may suggest to them ; 

 but the difficulty I experience is that men totally unacquainted 

 with the teachings of science are unable to surmount the unfore- 

 seen difficulties that present themselves in all experimental 

 inquiries ; consequently, many begin well, but never bring their 

 effort to a successful issue. It affords me, therefore, particular 

 pleasure to mention that, four years since, I succeeded in en- 

 gaging the co-operation of a number of intelligent men, for the 

 greater part former pupils of mine, in performing systematic 

 field experiments. 



On a former occasion, I published the results of field experi- 

 ments on clover-seeds, and also a short paper on the effect of 

 potash-salts and common salt on mangolds. 1 have now the 

 pleasure of laying before the Society short reports on similar 

 experiments on swedes, mangolds, and potatoes, which were 

 carried out under my direction in the years 1864, 1865, and 

 1866. According to a pre-arranged plan, the same artificial 

 VOL. III. — S. S. 2 L 



